Data communication system with automatic power control

ABSTRACT

A communication system comprised of a transceiver (101) for transmitting and receiving data signals and a modulation/demodulation apparatus (102) to modulate the data signals from an accessory (109) for transmission and demodulate data signals after reception by the transceiver (101). A processing device (103) controls power to the various components of the communication system.

This is a division of application Ser. No. 07/755,932, filed on Sep. 6,1991, now U.S. Pat. No. 5,392,023.

FIELD OF THE INVENTION

The present invention relates generally to the field of communicationsand particularly to automatic power control of a communication system.

BACKGROUND OF THE INVENTION

A radiotelephone/facsimile combination allows a user to transmit andreceive documents without having the constraints of a fixed office. Aradiotelephone/computer combination permits a computer user to access adata base or to contact other computer users with a portable computer,also without being tied down to an office. If the computer has theproper modem, documents can also be sent from the computer to afacsimile machine. A typical radiotelephone is described in detail inMotorola Micro T•A•C manual #68P81150E49 available from the assignee ofthe present invention.

The problem with these schemes, however, is that these combinations aretypically powered by a car's electrical system. To remain truly mobile,the radiotelephone/facsimile or radiotelephone/computer must be batterypowered, allowing the user to take the combinations anywhere. Thisresults in the combinations being powered by either one battery for bothunits of the combination or separately powering each unit with separatebatteries, requiring a larger and heavier combination. With either powerscheme, both units of the combination must either remain powered up toreceive an incoming call or the facsimile or computer turned on manuallywhen a telephone call is received that requires those units. In eithercase, the battery's usefulness will decrease due to the time the unitsare on and not being used. Even if the units are turned on and offmanually when a call is received, there is still the possibility of itbeing inadvertently left on and draining the battery.

A radiotelephone/computer user may also want to send data out via amodem that is connected to the radiotelephone. In this case theradiotelephone must be left on or turned on and off manually when it isneeded. There is a resulting need for a radiotelephone/computer orradiotelephone/facsimile combination that conserves battery power whennot active.

SUMMARY OF THE INVENTION

The communication system of the present invention is comprised oftransceiving means for transmitting and receiving data signals andmodulation/demodulation means to modulate/demodulate the data signalsfor transmission and after reception. Processing means controls theoperation of the communication system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of the data communication system.

FIGS. 2A and 2B show flow diagrams of the process used by the controllerof the communication system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The data communication system utilizes a bidirectional power controllerthat controls power to a radiotelephone and facsimile machine, computer,or other accessory coupled to the radiotelephone. Thus, when anaccessory is needed, power to that accessory is enabled.

The preferred embodiment of the data communication system is illustratedin FIG. 1. The system is comprised of a microprocessor ormicrocontroller (103) (hereinafter referred to as the controller) tocontrol the system. The controller (103) controls power switches(106-108) to an external accessory (computer, facsimile machine, etc.)(109), as well as to the modem (102) and radiotelephone (101), asrequired by the process of the present invention, illustrated in FIGS.2A and B. The power control switches (106, 108) to the accessory and theradiotelephone are coupled to ground while the switch (107) to the modemis coupled to the radiotelephone's battery or other power source.

The external accessory (109) communicates commands and data to thecontroller (103) via an asynchronous communications interface adapter(ACIA) (104). The controller (103)communicates commands and data to themodem (102) via another ACIA (111). If the external accessory (109)communicates over an RS-232 bus, a level translator (105) can be used toconvert the RS-232 logic levels to TTL levels.

The radiotelephone (101) is coupled to the modem (102) by theradiotelephone's audio line (110). The modem (102) can then transmit orreceive modulated data through the radiotelephone's transmitter orreceiver. In the preferred embodiment, the radiotelephone's batterypowers the modem (102). The battery is coupled to the modem (102)through a power control switch (107).

Referring to FIG. 2B, the radiotelephone is normally in a low-powerstand-by mode when turned on and not in use (201). The accessory, if notbeing used, is off or also in a low-power stand-by mode (201). The modemis off (201). When a call is received from a base station (202), theradiotelephone goes into an active mode to receive the call. The call isindicated by a received ring signal that is also coupled to thecontroller. The controller, in response to this ring signal, turns onthe accessory and the modem and the call is answered by theradiotelephone (203). Data is then received from the transmitting party.In one embodiment of the present invention, the controller can returnthe components of the system to their previous state of power (204).

If the accessory originates a command (205), the command is executed bythe controller (206). An example of such a command is for the datacommunication system to originate a data transfer.

This data transfer process is illustrated in FIG. 2A. For thisembodiment of the process, the accessory is on while the modem is offand the radiotelephone is off or in the standby mode. The accessorysends a command to the controller (220). If the controller determinesthe command is a power control command (221), the command is executed bythe controller (223), e.g., the controller turns on the radiotelephoneand modem. If the radiotelephone was already on and in the stand-bymode, the transmission of data will cause it to go into the active mode.

If the controller determines the command is to retrieve radiotelephonedata (224), the controller turns on the radiotelephone if it was off andretrieves the data (225). This data could include received signalstrength information (RSSI) or data from the radiotelephone's memory(i.e., telephone numbers).

If the controller determines the command is intended for the modem'sintelligent controller (222), the controller turns on the modem andpasses the command to the modem's controller (226). An example of such acommand is the "AT" dial command. The modem's controller can thentransfer the telephone number, attached to the command, to theradiotelephone for dialing. The accessory can now communicate, throughthe modem and radiotelephone, to another accessory that is using eithera radiotelephone or a landline telephone and a modem.

If the accessory (109) is a computer, a data modem can be used. Anexample of such a modem is a UDS V.22bis. If the accessory (109) is afacsimile machine, a facsimile modem can be used. An example of such amodem is a Worldport 2496.

Once the call has been completed, the controller (103) removes powerfrom the modem (102) and the radiotelephone (101). The accessory (109)is powered down by its own internal power-down algorithm. An alternateembodiment powers down the modem and radiotelephone automatically apredetermined time after the call has ended. Another alternateembodiment would power down the modem and radiotelephone a predeterminedtime after the last command has been sent from the accessory to theapparatus, if the radiotelephone is not in a call. Yet anotherembodiment would complete the power down procedure only after a commandwas sent from the computer instructing the power down to occur. Anotherembodiment could use the controlling controller to power-down theaccessory after transfer of the data.

The data communication system can be built into the accessory (109). Inalternate embodiments, the items of the communication system can be inseparate enclosures or share the same enclosures. Also in alternateembodiments, all the components of the present invention can share thesame power source or be combined in various combinations.

The data communication system described reduces the time a battery needsto power a modem combined with a radiotelephone by turning off bothcomponents when not needed. By reducing the time these components aredrawing power, the battery use can be greatly extended.

We claim:
 1. A power saving communications system comprising:a first power source for producing power; a radio telephone coupled to the first power source, for transmitting and receiving data signals and for generating a first power control signal; an accessory for transmitting and receiving data signals; a second power source for producing power; a modem coupled to the radio telephone and to the accessory for demodulating received data signals and modulating data signals to be transmitted; and a controller for coupling power from the second power source to the accessory in response to the first power control signal.
 2. A power saving communications system comprising:a first power source for producing power; a radio telephone for transmitting and receiving data signals; a second power source for producing power; an accessory coupled to the second power source that generates data signals and a second power control signal; a modem coupled to the radio telephone and to the accessory for demodulating received data signals and modulating data signals to be transmitted; and a controller for coupling power from the first power source to the radio telephone in response to the second power control signal.
 3. The power saving communications system according to claim 2, wherein the controller is responsive to the second power control signal for coupling power from the first power source to the modem.
 4. A power saving communications system comprising:a first power source for producing power; a modem for demodulating received data signals and modulating data signals to be transmitted; a radio telephone coupled to the modem, for transmitting and receiving data signals and for generating a first power control signal; a second power source for producing power; an accessory coupled to the modem for transmitting and receiving data signals and for generating a second power control signal; and a controller for coupling power from the first power source to the radio telephone in response to the second power control signal, for coupling power from the second power source to the accessory in response to the first power control signal, and for coupling power from the first power source to the modem in response to the first power control signal or the second power control signal.
 5. The power saving communications system according to claim 4, wherein the accessory is a computer.
 6. The power saving communications system according to claim 4, wherein the accessory is a facsimile machine. 